Telomerization is a reaction wherein a taxogen (X) is added to a telogen (AB) by application of heat or light under a suitable catalyst so that a polymer of low polymerization degree represented by the formula: A(X)mB (wherein m is generally in the range of 1 to 20), that is, a telomer is obtained. An example of telomerization known in the art is a reaction wherein a fluoroalkyl iodide is used as the telogen and tetrafluoroethylene is used as a taxogen and another fluoroalkyl iodide having the molecular weight higher than the telogen is obtained. This reaction can be regarded as a reaction for obtaining a tetrafluoroethylene adduct compound by adding tetrafluoroethylene to the telogen. Various methods utilizing this reaction for obtaining the industrially useful fluoroalkyl iodide have been proposed. Hereinafter, several examples of the methods are recited. It should be noted that in order to discriminate a fluoroalkyl iodide as a product from another fluoroalkyl iodide as a starting material, the former is referred to as a “fluoroalkyl iodide telomer.”
U.S. Pat. No. 3,226,449 discloses a method for producing a perfluoroalkyl iodide telomer by means of a telomerization wherein tetrafluoroethylene is added to a perfluoroalkyl iodide using an organic peroxide as an initiator. The telomerization is carried out in a single step in a single reactor.
GB Patent 1,256,818, Japanese Patent Publication (Kokoku) No. 60-22687 (1985), U.S. Pat. No. 3,234,294, U.S. Pat. No. 3,404,189 and GB Patent 1,189,576 disclose a method for initiating a telomerization which is employed upon producing a perfluoroalkyl iodide telomer.
Japanese Patent Laid-Open (Kokai) Publication No. 6-206908 (1994), Japanese Patent Laid-Open (Kokai) Publication No. 6-305995 (1994), and Japanese Patent Publication (Kokoku) 7-59525 (1995) explain that the number of carbon atoms (or molecular weight) of a perfluoroalkyl iodide telomer needs to be in a specific range, and disclose methods for producing a perfluoroalkyl iodide telomer having the desired number of carbon atoms by means of telomerization degree is controlled by employing a specific procedure and a reactor having a specific shape.